Zoom objective lens

Abstract

The invention relates to a zoom objective lens with continuously adjustable magnification, comprising five lens groups, where the first lens group, the second lens group and the fifth lens group are fixed in relation to an object. The third lens group and the fourth lens group are axially displaceable. The following conditions apply to the lens: the variable air gap between the second lens group and the third lens group decreases or has a turning point with a transition from a low to a high magnification β, the refractive power of the second, third and fifth lens groups is positive and the refractive power of the fourth lens group is negative.

The invention claimed is: 
     
       1. A zoom objective lens with continuously adjustable magnification β, comprising five lens groups, the first lens group, the second lens group and the fifth lens group being fixed in relation to an object and the third lens group and the fourth lens group being axially displaceable, in which the following conditions apply:
 a variable air gap between the second lens group and the third lens group decreases or has a turning point with a transition from a low to a high magnification β, 
 the refractive power of the second, third and fifth lens groups is positive and 
 the refractive power of the fourth lens group is negative, 
 wherein the first lens group is a single meniscus lens, 
 wherein the second lens group consists of a maximum of two individual lenses, each having a positive refractive power, and a cemented lens component consisting of a maximum of three lenses, 
 wherein the third lens group has either two individual lenses or a dual cemented lens component, 
 wherein the fourth lens group consists of either a dual cemented lens component or a dual cemented lens component and an individual lens, wherein the dual cemented lens component has a meniscus lens, the centers of curvature of which lie on the object side, and 
 wherein the fifth lens group is a dual cemented lens component, in which the biconvex lens lies on the image side. 
 
     
     
       2. The zoom objective lens according to  claim 1 , with a parfocal length of 60 mm and a structural length of ≤63.56 mm, the parfocal length being the length from the object plane to the objective lens mounting surface in front of a back stop, and the structural length being defined as the length from the object plane to the back stop. 
     
     
       3. The zoom objective lens according to  claim 1 , characterized in that, for displacing the third lens group and the fourth lens group, two adjustment elements are provided, which are actuated manually or by a motorized mechanism, in each case by means of a correcting ring. 
     
     
       4. The zoom objective lens according to  claim 1 , characterized in that the lenses have rims for the purpose of delimiting the beam bundle. 
     
     
       5. The zoom objective lens according to  claim 1 , characterized in that no aperture with an adjustable diameter for adjusting the magnification is provided. 
     
     
       6. A zoom objective lens with continuously adjustable magnification β, comprising five lens groups, the first lens group, the second lens group and the fifth lens group being fixed in relation to an object and the third lens group and the fourth lens group being axially displaceable, in which the following conditions apply:
 a variable air gap between the second lens group and the third lens group decreases or has a turning point with a transition from a low to a high magnification β, 
 the refractive power of the second, third and fifth lens groups is positive and 
 the refractive power of the fourth lens group is negative, 
 wherein the first lens group is a cemented lens component, in which a front lens of the first lens group has a flat surface oriented toward the object side, 
 wherein the second lens group consists of a maximum of two individual lenses, each having a positive refractive power, and a cemented lens component consisting of a maximum of three lenses, 
 wherein the third lens group has either two individual lenses or a dual cemented lens component, 
 wherein the fourth lens group consists of either a dual cemented lens component or a dual cemented lens component and an individual lens, wherein the dual cemented lens component has a meniscus lens, the centers of curvature of which lie on the object side, and 
 the fifth lens group is a dual cemented lens component, in which the biconvex lens lies on the image side. 
 
     
     
       7. The zoom objective lens according to  claim 6 , with a parfocal length of 60 mm and a structural length of ≤63.56 mm, the parfocal length being the length from the object plane to the objective lens mounting surface in front of a back stop, and the structural length being defined as the length from the object plane to the back stop. 
     
     
       8. The zoom objective lens according to  claim 6 , characterized in that, for displacing the third lens group and the fourth lens group, two adjustment elements are provided, which are actuated manually or by a motorized mechanism, in each case by means of a correcting ring. 
     
     
       9. The zoom objective lens according to  claim 6 , characterized in that the lenses have rims for the purpose of delimiting the beam bundle. 
     
     
       10. The zoom objective lens according to  claim 6 , characterized in that no aperture with an adjustable diameter for adjusting the magnification is provided.